This invention relates to phenylquinoxaline resin compositions.
The acetylene-terminated polyphenylquinoxalines disclosed in U.S. Pat. Nos. 3,966,729 and 4,147,868 represent promising new matrix resins for advanced structural materials. These materials propagate and cure by addition reactions to form high molecular weight, thermally stable compositions. The addition process obviates all problems associated with volatile by-product formation that occurs when such materials are prepared by condensation processes.
The thermally induced free radical polymerization of aromatic and heterocyclic diacetylenes provides a linear conjugated polyene of 6 to 8 repeating units which results in a cluster-shaped species whose growth is inhibited by the steric hindrance of the monomer or oligomer backbone structure. Although the free radical at the hub of the cluster is reactive its growth becomes increasingly more difficult as the reaction proceeds, reaching a finite limit. Subsequent reaction of dangling acetylene groups of a cluster results in a highly cross-linked polyene network. Such cross-linking has a direct effect on the network topology which manifests itself in mechanical behavior.
It is an object of the present invention to provide novel quinoxaline resin systems having a low crosslink density.
Other objects and advantages of the present invention will be apparent to those skilled in the art.